Visualizations have previously followed the basic lines of the classic oscilloscope look, but have recently begun to embrace 3D Accelerators to to some amazing 3D audio representations.

A lot of graphics coders who were too young to get in on the Demo Scene (when it was 'the big thing') have embraced the visualization world (and to a lesser extent, the Skin world) -- it is certainly one of the best places to flex your graphics coding skills.